Known to exist in the relevant industry today are devices which provide one-way, cam locking of a collar on a cylindrical bar. These prior art devices are comprised of a collar apparatus, sometimes referred to as the "quick release collar", for mounting on a cylindrical bar. The quick release collars include, basically, a cylindrical, inner shell with an axial passage for accepting the cylindrical bar and an outer sleeve positioned outside and coaxial with the inner shell, a space being defined between the inner shell and the outer sleeve. The inner shell is defined with a plurality of radial openings and a radially movable ball is located in each of the openings in the shell. A tension ring is rigidly attached to the outer sleeve in the space between the sleeve and the shell. The sleeve and the tension ring are axially slidable with respect to the inner shell between a locked position and an unlocked position. The tension ring has a tapered inner surface portion adjacent to the movable balls. The inner surface portion is tapered to provide a relatively small diameter adjacent to the movable balls in the locked position and a relatively large diameter adjacent to the movable balls in the unlocked position, such that the radial positions of the movable balls depend on the axial position of the tension ring. The spring biases the sleeve and tension ring axially toward the locked position so that the tension ring cams the movable balls inwardly into frictional engagement with the bar. The inner shell and outer sleeve are manually spreadable to move the tension ring axially toward the unlocked position so that the balls move outwardly.
The operation of the prior art, quick release collars is such that, as the collar moves relative to the bar (bar inserted into the collar passage) in a first axial direction, the collar balls and tension ring remain in the unlocked position and the collar moves freely along the bar without locking. However, as the collar moves relative to the bar in the opposite (second) axial direction, the collar balls and tension ring function in the locking position and the collar grips the bar to resist relative movement of the collar and bar. As mentioned above, once the collar has gripped the bar, the "lock" is released by manually spreading the inner shell and outer sleeve to release the frictional engagement between the balls and tension ring.
In the manner generally discussed above, the prior art, quick release collars effect a gripping resistance to relative axial movement between the collar and bar, while providing a quick release of the grip. It is noted that once the grip has been released, the collar may now move freely in the first direction, relative to the bar; but, should the collar be moved again in the second, relative direction, it will again "lock" onto the bar. This one-way axial freedom of movement causes severe limitations in the practical applications of the prior art quick release devices. Furthermore, it is a noted characteristic of the quick release collars that, as the prior art devices are subjected to vibration, while locked onto the bar, the grip becomes tighter-and-tighter as the balls move further-and-further up the tapered cam surface of the tension ring. As the grip becomes tighter, it sometimes becomes extremely difficult to spread the inner shell and outer sleeve to release the collar. Thus, this characteristic, also, creates a limitation to the practical applications for the prior art quick release collars.